1.A flat plane cutting through a three-dimensional object, usually at right angles to the longest axis of the object.
2.Any visual representation of a cross section 1, showing the internal structure of the object in the plane of the cross section; as, the technician prepared a series of MRI cross sections of the skull. Note: Different cross sections created by different techniques may show different aspects of internal structure. Thus computerized axial tomography using X-rays shows different structures than are visualized by MRI.
3.A thin slice of an object made by cutting it transversely; as, to view a cross section of a bacterium with an electron microscope after staining the DNA; cross sections were prepared with a microtome.
4.A representative sample of a complex group; as, the town contained a cross section of the American population.
5.(Physics) A measure of the probability that a nucleus will interact in a specified way with a bombarding particle, expressed as the effective area that the nucleus presents to the particle; called also nuclear cross section.
